The patient with concussion is one who, with or without brief unconsciousness, has recovered to nearly normal in a limited time. Just which patients are apt to do this is a process of exclusion. This article is a mixture of what to look for, what to do and what findings rule out simple concussion. While repeated observation of level of consciousness, airway control and careful assessment of vital signs usually rule out serious injury, we must be on our toes to avoid serious mistakes.